A touch panel (touch screen) is a device for inputting information to an information processing device, such as a computer etc., in an interactive manner by touching (pressing) the panel using a finger, a pen, etc.
There are different types of touch panels based on different operating principles: resistive; capacitive; infrared; ultrasonic; electromagnetic inductive; etc. Resistive and capacitive touch panels are recently most commonly used in display devices etc., because of the low cost of mounting.
The resistive touch panel includes, for example, a pair of substrates facing each other, a pair of transparent conductive films provided as resistive films on inner surfaces of the pair of substrates, an insulating spacer interposed between the pair of substrates to form an air layer between the pair of transparent conductive films, and a position detection circuit which detects a touch position. The resistive touch panel is, for example, mounted on the front surface of the display screen of a liquid crystal display panel.
In the resistive touch panel thus configured, when the front surface of the touch panel is touched, the pair of transparent conductive films contact each other (make a short circuit), so that a current flows between the pair of transparent conductive films. Based on a change in voltage when a current flows between the pair of transparent conductive films, the position detection circuit detects the touch position.
For example, PATENT DOCUMENT 1 describes a resistive transparent touch panel in which a non-reactive silicone oil is interposed between a transparent substrate and a resistive film provided on another transparent substrate, adhering to a surface of the resistive film.